I searched, but to no avail, so I figured I would start a post that could possibly be a reference in the future. I hear talk of ported exhaust manifolds, and think it might be something I want to do for just that little bit better performance. I have several questions. 1. How much and what does it help? Spool, power? 2. Where exactly should material be removed? 3. How does it compare to a tubular manifold? I'm sure not the same power, but I'm betting a boat load cheaper.
Exhaust manifold porting questions
- Thread starter SupraMan1987
- Start date
= Power+spool . Ports should shine Head+manifold . Mostly remove alot under the Turbo mount . It should be vee shaped.Alot can be taken from there...+++ ^:icon_razz
if im not mistaken the exhaust ports on the head should be left alone. they prevent reversion from the pressure caused with the turbo iirc... poodles has stated this a few times and a few others. Make sure to search before you chew into it!
the mani can be hacked to bits though. the "bumps" that hold the heat shield studs in are said to leak or crack when ported smooth so they need to be welded. I cant recall the porting method used but IJ has said it a few times. It will actually get to the ports in the manifold and not just as far as your grinder/ dremel reaches. Again searching would have yielded all of this (google works along with SF), good luck
the mani can be hacked to bits though. the "bumps" that hold the heat shield studs in are said to leak or crack when ported smooth so they need to be welded. I cant recall the porting method used but IJ has said it a few times. It will actually get to the ports in the manifold and not just as far as your grinder/ dremel reaches. Again searching would have yielded all of this (google works along with SF), good luck
the process is called extrude honing.
I my semi-qualified opinion, when it comes to our stock exhaust manifold, all you really want to do is get rid of the lumps formed by the heat shield studs and smooth the inner surfaces of the manifold. Any significant enlargement of the tubes will reduce the velocity of the exhaust gas, slowing spool. Polishing the surfaces will help increase the gas velocity.
I my semi-qualified opinion, when it comes to our stock exhaust manifold, all you really want to do is get rid of the lumps formed by the heat shield studs and smooth the inner surfaces of the manifold. Any significant enlargement of the tubes will reduce the velocity of the exhaust gas, slowing spool. Polishing the surfaces will help increase the gas velocity.
You dont want to touch the head, if anything you can polish the inside of the exhaust ports but dont remove any material. IMO its not really worth it because after the first start up they will be covered in carbon anyway. As for the manifold. you can smooth out the excess material where the studs for the heat shield are but dont take them all the way smooth, you need something there. You should also port the divider, taking meat off this and sharpening the edge will help. Theres some pictures in my build thread in my sig, you can take a look at that for reference.
Total WOTM, for the amount of time and effort you put into porting the stock manifold you'd be better buying an e-bay tubular.
When you port a stock manifold you at best can reach 3" inside leaving the bulk unported.
Turbo headers are usually made from thickwall tube so aren't as noisy as a traditional NA header (they can ring at certain frequencies)
When you port a stock manifold you at best can reach 3" inside leaving the bulk unported.
Turbo headers are usually made from thickwall tube so aren't as noisy as a traditional NA header (they can ring at certain frequencies)
I think if you have access to air tools and a porting bit, this could be a "free mod". I also wonder if porting the stock exhaust manifold (weakening it) puts that much more stress on the manifold which seems overbuilt from the factory? What if you smoothed, polished the compressor housing and ported the CT26? Would you be able to remove enough material to relieve stress from the turbo's weight? (I realize no one will or has tested something like this but how maybe someone knows how much weight can be removed from a CT26 turbo?
Also it would be cool to keep a "sleeper" stock manifold.
Also it would be cool to keep a "sleeper" stock manifold.
IJ.;1248006 said:
I consider labor free...even it may be several hours worth of work, and I don't think anyone's counting an electric bill on their costs.
Carbide cutters aren't cheap.... polishing rolls or flappers aren't cheap.
Labour isn't "free" no matter who you are your time is worth something and to invest it into a job that may not show ANY improvement is just plain stupid.
As I said earlier you can only reach so far inside with cutters so you're at best doing a 30% port job so again a total WOTM..
Labour isn't "free" no matter who you are your time is worth something and to invest it into a job that may not show ANY improvement is just plain stupid.
As I said earlier you can only reach so far inside with cutters so you're at best doing a 30% port job so again a total WOTM..
IJ.;1248394 said:
I meant if you had the bits and tools, I haven't worn out my bits yet and I've ported two 4G63 manifolds. I come from the DSM world where "every little bit counts" so my opinion is just an option for the right person, your going to have to put labor in your car, this is a way to spend it, gain or not.
IJ, I know you (as well as me) wouldn't do such work as we didn't cheap on our projects, that's why we sport tubular manifolds and turbos that can put out more than 20psi efficiently.
What tubular manifold would you guys suggest then? I'd like to be able to keep factory intercooler piping routing, as I have an HKS setup
ebay ones... im not sure how the dp will fit with an adapter plate for the t4-t3 flange...
if anyone runs a stock or direct replacement DP with one of these id like to know...
if anyone runs a stock or direct replacement DP with one of these id like to know...
